Post on 22-Dec-2015
transcript
Chapter 13
Pain- A Fundamental Stress
Pain: Urgent Signals
• Hunger, Thirst, Breathing
• Muscles, Joints, Heart, Stomach
• Wounds, Damage, Swelling
• Headaches,
• Worry, Fret, Anxiety
Pain
• A signal
• Important information for the brain
• A signal that can’t be ignored
• Localizable
Pain Signals
• Pain receptors
• Spinal cord
• Nerves
Pain Stimuli
• Stretch
• Damage
• Reduced blood flow
Reflex to Pain
Fast Track Sympathetic Reflex
Slow track Attention
Localization
Referred Pain
Physiology of Pain Control
Proopiomelanocortin mRNA
ACTH Endorphin
Enkephlin
Message Splicing
Pain Control
Why?
A Medical Problem
Pain Control
• Generation of pain signal
• Transmission of pain signal
• Sympathetic response to pain
• Long term stress response
• Perception of pain
• Limbic response to pain
Non-drug Methods
• Bit the bullet: competition for attention in the reticular core of the brain
• acupuncture
Local Anesthetics
• Uses– Creams - pain receptors– Inject into the area of the nerve– Spinal block
Local Anesthetics
• Oily compounds
• Dissolve into membranes
• Disrupt membrane function in the area
• Removed by circulation
• Novocain, lidocain, tetracain
• Penetrance, potency, and metabolism
anesthetic
Block signal from getting to the central nervous system
Side Effects
• Spinal block – headaches
• All uses – general depressant
• Other excitable tissues
Non-Narcotic Analgesics
• Over the counter
• Low level pain
• Do not alter consciousness
Aspirin-like Compounds
• Prehistory- willow bark tea
• Good for headaches, muscle aches, joint pain
• Not good for internal organ pain due to stretch
• Blocks COX1 and COX2 – prostaglandin synthesis
Aspirin-like Compounds Side Effects
• Reduces fever
• Reduces inflammation
• Inhibits blood clotting
• Increases respiration
• Irritates stomach
• Reye’s syndrome
Acetaminophen
• Older drug was phenacetin which was converted by liver to acetaminophen
• Only blocks prostaglandin synthesis in the CNS not peripheral
• Not anti-inflammatory
Acetaminophenside effects
• Reduces fever
• Liver toxicity
• Kidney toxicity
• Other drug interactions (eg alcohol)
Ibuprofen and Naproxen
• Formerly prescription (dosage)
• Interferes with prostaglandin synthesis
• Reduces fever
• Reduces inflammation
• Rare toxic amblyopia
Narcotic Analgesics
• Intense pain
• Opium – from the unripe seed pod of a type of poppy
• Morphine, codeine (natural)
• Heroin, dihydromorphine (semi-synthetic)
• Methadone, meperidine (synthetic)
Pain Threshold
A Balance
Opiate Receptors
• Pain paths in spinal cord
• Medulla (breathing)
• Hypothalamus
• Limbic system
• Frontal and temporal lobes
• Reticular core
• Outside CNS – digestive system
Opiate Use
• Short term intense pain
• Why not long term?– Tolerance– Dependence– Addiction
Opiate Side Effects
• Suppresses drives – hunger, thirst, sex
• Hypothalamic control of temperature and hormones
• Medulla control of breathing
• Stimulates emetic reflex
• Inhibits cough reflex
• Pin point pupils
Pain
• Urgent signals
• Balance of important priorities
• Useless pain